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Draining inside foundation walls before slab pour

tyler_2 | Posted in General Questions on

I’m a slow, broke, owner builder of a new 870 square foot home. I’ve got clay soils. I have stepped footers and a stem wall coming up to about a foot above grade on the high side and 4 feet above grade on the low side. That is all poured.

Right now I have a mound of local fill inside the walls that I need to spread out and compact. There’s a tarp over the mound. Eventually there will be a slab on top of all of this. The tops of the footers are exposed on the inside and outside of the wall.

When it rains, water (mostly) runs off the tarp to the outside edges. It hits the top of the footers, and finds the low point, where there is a small 3″ sleeve in the foundation wall about an inch above the footer. It flows out of that, and down the hill.

In about a week, the walls will be cured enough to run the compactor, so I’ll need to start leveling and compacting this sub-slab fill.

My concern is that when I start doing this, I will immediately lose my ability to drain water that falls inside the foundation walls. I was initially going to go nuts and put foundation drains around the inside. Then I pondered whether I could just put an 8 inch strip of 3/4 stone wrapped in filter fabric around the inside and slowly build that up as I build up the fill – the drawback to this is just my questioning whether the fill will settle the same way as 3/4 clean stone around the edges and cause slab problems later. Or I could just always have a 6″ hole at a perceived low spot and have the sump pump raining.

1. What would you do to give the inside a chance to drain, so that you have a chance to compact clay that isn’t mud, between rains?
2, bonus question. Would you bother with footer drains around the exterior?

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  1. 5Stud | | #1

    Perforated weeping tile is way cheaper than rock.
    You can put a sock over it if the soil conditions demand it.
    a Canadian google search.

    bonus question answer: yes

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